Method of and means for reversing motors.



A. S. GUBITT.

METHOD OF AND MEANS FOR BEVERSING MOTDBS.

APPLICATION FILED JUNE 3, 1909.

960,000. Patented May 31, 1910.

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ARCHIBALD S. CUBITT, OF PITTSFIELD, MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

METHOD AND MEANS FOR, IREVERSING MOTORS.

' Application filed June 3, 1909. Serial No. 499,860.

To all whom it may concern:

Be it known that I, ARCHIBALD S. CUBrr'r, asubject of the King of Grreatv Britain, residing at Pittsfield, county of Berkshire, State of Massachusetts, have invented certain new and useful Improvements in Methods of and Means for Reversing Motors, of which the following is a specification.

In electrically driven railway cars or locomotives in which four driving motors are employed the motors are often normally operated in pairs, the motors of each pair being always connected in parallel with one another. \Vith such an equipment the pairs of motors are first connected in series and then in parallel, thereby giving what is called series parallel and full parallel operation. In such systems it has heretofore been the custom to reverse the motors by reversing the armature-s with reference to the fields of the motors, this being accomplished by opening the armature circuitand closing it again in reverse connection Willi reference to its field; A motor c ntrol sys tem of this type is shown in the patent to F. E. Case, 809,773, dated January 9, 1906.

lVith systems of the kind above referred to it has been the custom under emergency conditions for the operator to throw his reverser to the reverse position thereby connecting each pair of motors in a closed circuit and allowingoneto act a generator to pump current through the other motor acting as a motor. This action will take place owing to the residual magnetism in the fields of the motors and to the fact that as the fields are never exactly the same the voltage of one motor will be higher than the voltage of the other and current will commence to flow from one to the other through the closed circuit established by the reversing switch. It has been found that when a control system 01: this kind is operated in this manner, if the operator throws his reverser back again to its original position before the car has come to rest, the interruption of the current flowing in the closed circuit through each pair of motors will cause serious arcing at the contacts of the reverser owing to the fact that the closed circuit is interrupted during the process of reversal.

My invention consists in providing a new and improved method of and means for reversing the motors in a two or four motor Specification 0f Letters'latent.

Patented May 31, 1910.

equipment, such that the burning of the contacts during reversing will be effectively prevented. To this end, instead of reversing the armature with relation to the field of each motor, I reverse the field with reference to the armature and arrange for the short circuiting of said fields during the operation of reversal. In this way the field of each motor is killed during reversal and the voltage of the motors is reduced practically to zero, thereby reducing the current in the circuit substantially to zero and removing all danger of arcing at the contacts of the reversing switch.

In carrying out my invention I provide a reversing switch of the finger and segment type having a forward and reverse position and a transition position in which certain of the fingers bridge the spaces between certain segments and effectthe short circuiting of theme-tor fields in changing from forward to reverse connections.

Referring to the drawing, Figure 1 shows diagrannnatically four motors and a reversing switch for controlling the motor connections in accordance with my invention;

and Fig. 2 is an end elevation of a portion of the reversing switch showing the relation of the segments and fingers,

In Fig. 1 the armatures of the motors are shown at 1, 2, 3 and 4; and their series fields at 5, 6, 7 and 8. The drum of the reverser, which is shown developed in the usual manner, is provided with eight pairs of segments 9 and 10 arranged, as shown, in four groups in which the segments are crossconnected, as clearly indicated. \Vith these segments, cooperate fingers 11 and 12 connected, as shown, to the circuits leading to the armatures and fields. In the forward position, the fingers engage with the segments on the lines F F, as shown, while in the reverse position the fingers and segments engage on the lines R R. The middle lines F and B may coincide if it is desired to keep the angular movement of the switch small. The space between the segments 9 and 10 is made small enough so that the fingers 12 will, for an instant while the drum is moved from its forward to its reverse position or vice versa, bridge the space and connect the segments 9 and 10.

In Fig. 2 the drum of the reverser is which is not shown, being attached to the lugs 16 and 17. The drum 13, which may of insulating material, carries the segments 9 and 10. The fingers 11 and 12, which cooperate with the segments 9 and 10, are secured by bolts 18 and 19 on the side frames 20 and 21. As shown in Fig. 2, the reverser drum is in its midosition and finger 12 is bridging the gap Between the segments 9 and 10.

From an inspection of the diagram of Fig. 1 it will be clear that in the forward position of the reverser the motors of each pair will be connected in parallel with one another with their fields and armatures in a certain relation, while in the reverse position of the reverser the motors will be connected in parallel with their fields reversed in relation to their armatures. It will also be clear that in throwing from one position to the other the fingers 12 by bridging the gaps between the segments 9 and 10 will or an instant short circuit the fields, thereby obtaining the results explained above.

While I have shown but one arrangement for carrying out my improved method of reversing two motors normally operated in parallel, I do not intend to limit myself thereto, except as called for by the followin claims.

at I claim as new and desire to secure by Letters Patent of the United States, 1s:

1. The method of reversing simultaneously two motors normally operated in parallel which consists in short-circuiting the fields by establishing the reverse connections between said fields and their armatures while the original connections still exist and then interrupting the original connections.

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connections between said fie ds. and their armatures while the original connections still exist and then interrupting the original nnections.

3. In combination with two motors normally operated in parallel, aireverser of the finger and segment type having a forward and reverse tion 1n which certam position and a transition posiof the fingers bridge e space between segments in the same line and effect the short circuiting of the motor fields in changing the relation of the latter with reference to their armatures. 4. In combination wlth two motors normallyoperated in parallel, a reverser of the finger and segment type having four groups of two segments eac two fingers cooperating with each group of segments, the space between the se gments in each group being small thatat is bridged by one of the fingers when the reverser is thrown from one position to ar e short 'circuited in effecting t e reversal of their connections with their armatures.

my hand this 28th day of May,

In witness whereof, I have hereunto set ARCHIBALD S. OUBITT.

the other whereby the fields 

